The invention relates generally to a carton aligner for lateral alignment of cartons, or packages, on a conveying surface and more particularly to selective left-hand or right-hand alignment of packages. The invention is particularly adapted to providing proper lateral orientation of packages for sortation systems capable of opposite-direction diverting of packages.
Two-way, or bi-directional, sortation systems that are capable of diverting packages laterally to spurs extending in opposite directions are well-known. An example is the system disclosed in U.S. Pat. No. 3,361,247 to Lauzon et al. Certain such two-way sortation systems require packages to be positioned on the same lateral side of the sortation system as the spur to which the package is to be diverted. One such sortation system is disclosed in commonly assigned U.S. Pat. No. 3,269,519, issued to M. J. DeGood et al.
It is usually desirable to be able to maintain the longitudinal edge-to-edge spacing, or gap, between packages that are discharged to a sortation system. Induction subsystems are known that are capable of precisely establishing a desired spacing, or gap, between packages in order to enhance the through-put of the system. One such induction system is disclosed in commonly assigned U.S. Pat. No. 5,038,911, issued to Martin R. Doane et al for CONTROLLED SPACING FROM PLURAL LINES. Once a precise gap has been established between packages, it is desirable to be able to maintain the desired gap while providing the necessary two-way edge alignment required for the above mentioned two-way sortation systems. If such desired gap cannot be maintained, then additional spacing must be provided between packages in order to accommodate the variability in spacing. Such additional gap, of course, reduces the through-put of the system.
Known types of edge alignment systems tend to distort the spacing between packages. One such system is a herringbone roller bed which uses rollers that are positioned at an angle to the direction of package movement in order to laterally divert packages against a rail to provide the left-hand or right-hand alignment. The difficulty is that smaller packages must be laterally diverted a greater distance in order to provide the necessary edge alignment. Because the packages are diverted along the hypotenuse of a triangle, the greater lateral movement of smaller packages provides an increase in the total distance moved, which distorts the spacing with the packages in front of, and trailing, the given package. Therefore, the width of each particular package, or carton, affects the gap with packages in front of and behind it.
Another known edge alignment system utilizes a moving vertical belt positioned in the path of package travel at an angle with respect to the direction of travel in order to laterally divert the cartons. The aligner has a portion that is initially contacted by packages and is at a steep angle with respect to the direction of travel of packages in order to laterally divert the packages. The angle of the belt becomes less steep, through one or more angle changes, further downstream in order to re-turn the edge-aligned cartons to their original front-to-back alignment, so that the cartons are not turned on the conveyor. Because the belt is on an angle with respect to the conveying surface, the angle and speed of the belt affects the rate of travel of each diverted package. As the angle becomes more shallow, there should be a commensurate change in the belt speed in order to compensate for the difference in angle. However, this is not usually possible because such belt alignment systems typically only have one belt which can only have one speed. Therefore, there is a change in the speed, and hence the gap between packages of different widths and between diverted versus non-diverted packages.